Site 367: Cape Verde Basin

Party, Bukry The Shipboard Scientific

doi:10.2973/dsdp.proc.41.103.1978

Cited by 7 publications

(5 citation statements)

References 15 publications

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“…With the exception of well CM1 located on the continental shelf, the sedimentary rocks from the DSDP sites were deposited in deep pelagic environments occasionally influenced by distal turbidity currents (Jansa et al, 1978). Samples from DSDP sites were dated according to the biostratigraphical scheme defined for each DSDP site (Cepek, 1978;Cool et al, 2008;Foreman, 1978;Hayes et al, 1972;Lancelot et al, 1978;Lancelot & Winterer, 1980;Pflaumann & Cepek, 1982;Williams, 1978). The time resolution of samples is at the substage level (i.e., 2 to 3 Ma) for the Late Albian-Turonian interval and at the stage level (i.e., 5 to 10 Ma) for other intervals, which is sufficient to identify long-term trends in sedimentary provenance (Figure 2).…”

Section: Samplingmentioning

confidence: 99%

Geochemical Evidence for Large‐Scale Drainage Reorganization in Northwest Africa During the Cretaceous

Mourlot

Roddaz

Dera

et al. 2018

Geochem Geophys Geosyst

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West African drainage reorganization during Cretaceous opening of the Atlantic Ocean is deciphered here from geochemical provenance studies of Central Atlantic sediments. Changes in the geochemical signature of marine sediments are reflected in major and trace element concentrations and strontium‐neodymium radiogenic isotopic compositions of Cretaceous sedimentary rocks from eight Deep Sea Drilling Project (DSDP) sites and one exploration well. Homogeneous major and trace element compositions over time indicate sources with average upper (continental) crust signatures. However, detailed information on the ages of these sources is revealed by neodymium isotopes (expressed as ɛNd). The ɛNd(0) values from the DSDP sites show a three‐step decrease during the Late Cretaceous: (1) the Albian‐Middle Cenomanian ɛNd(0) values are heterogeneous (–5.5 to −14.9) reflecting the existence of at least three subdrainage basins with distinct sedimentary sources (Hercynian/Paleozoic, Precambrian, and mixed Precambrian/Paleozoic); (2) during the Late Cenomanian‐Turonian interval, ɛNd(0) values become homogeneous in the deepwater basin (–10.3 to −12.4), showing a negative shift of 2 epsilon units interpreted as an increasing contribution of Precambrian inputs; (3) this negative shift continues in the Campanian‐Maastrichtian (ɛNd(0) = −15), indicating that Precambrian sources became dominant. These provenance changes are hypothesized to be related to the opening of the South and Equatorial Atlantic Ocean, coincident with tectonic uplift of the continental margin triggered by Africa‐Europe convergence. Finally, the difference between ɛNd(0)values of Cretaceous sediments from the Senegal continental shelf and from the deepwater basins suggests that ocean currents prevented detrital material from the Mauritanides reaching deepwater areas.

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Section: Samplingmentioning

confidence: 99%

Geochemical Evidence for Large‐Scale Drainage Reorganization in Northwest Africa During the Cretaceous

Mourlot

Roddaz

Dera

et al. 2018

Geochem Geophys Geosyst

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“…Therefore it has been suggested that the deeper bottom waters (>3000 m) of the proto-North Atlantic were predominately oxic and that a large part of the OC-enrichment of mid-Cretaceous black shales at site 367 resulted from redeposition of sediments deposited where the OMZ impinged on the seafloor [Arthur et al, 1984]. Indeed, thin turbidites consisting of quartz silt or clayey foraminifer sand do occur but apparently represent only a minor component of the late Cenomanian section [see also Shipboard Scientific Party, 1977]. To the best of our knowledge, no direct evidence has so far been provided for a turbiditic origin of the OM-rich black shales itself [see Arthur et al, 1984, and references therein], and thus we believe that the deeper bottom waters were predominately anoxic during their deposition (see below).…”

Section: Stratigraphy and Palaeosettingmentioning

confidence: 99%

Enhanced productivity led to increased organic carbon burial in the euxinic North Atlantic basin during the late Cenomanian oceanic anoxic event

Kuypers¹,

Pancost²,

Nijenhuis³

et al. 2002

Paleoceanography

280

305

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[1] Three Cenomanian/Turonian (C/T, $93.5 Ma) black shale sections along a northeast-southwest transect in the southern part of the proto-North Atlantic Ocean were correlated by stable carbon isotope stratigraphy using the characteristic excursion in d 13C values of both bulk organic matter (OM) and molecular fossils of algal chlorophyll and steroids. All three sites show an increase in marine organic carbon (OC) accumulation rates during the C/T Oceanic Anoxic Event (OAE). The occurrence of molecular fossils of anoxygenic photosynthetic green sulfur bacteria, lack of bioturbation, and high abundance of redox sensitive trace metals indicate sulfidic conditions, periodically reaching up into the photic zone before as well as during the C/T OAE. During the C/T OAE, there was a significant rise of the chemocline as indicated by the increase in concentrations of molecular fossils of green sulfur bacteria and Mo/Al ratios. The presence of molecular fossils of the green strain of green sulfur bacteria indicates that euxinic conditions periodically even occurred at very shallow water depths of 15 m or less during the C/T OAE. However, bottom water conditions did not dramatically change as indicated by more or less constant V/Al and Zn/Al ratios at site 367. This suggests that the increase in OC burial rates resulted from enhanced primary productivity rather than increased anoxia, which is supported by stable carbon isotopic evidence and a large increase in Ba/Al ratios during the C/T OAE. The occurrence of the productivity event during a period of globally enhanced organic carbon burial rates (i.e., the C/T OAE) points to a common cause possibly related to the formation of a deep water connection between North and South Atlantic basins.

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“…Site 367 (12°29.2′N; 20°02.8′W) was drilled in 1975 during the DSDP Leg 41 and is located off the coast of the Senegal in the Cape Verde Basin (Figure 1). This site shows an almost continuous sedimentary record from Upper Jurassic (Oxfordian-Kimmeridgian) up to Pleistocene (Lancelot et al, 1978). During the Cretaceous, this site belonged to the southern part of the Central Atlantic and a paleodepth of around 3,700 m has been estimated based on isostatic methods (Chenet and Francheteau, 1979).…”

Section: Sampling Locationmentioning

confidence: 90%

The Plenus Cold Event Record in the Abyssal DSDP Site 367 (Cape Verde, Central Atlantic): Environmental Perturbations and Impacts on the Nitrogen Cycle

et al. 2021

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The Oceanic Anoxic Event 2, at the Cenomanian-Turonian boundary (∼93.9 Ma), was an episode of widespread burial of organic matter in marine sediments, underlined by a positive carbon-isotope (δ13C) excursion observed worldwide. Within this episode of O2-depleted conditions, a short interval of cooling, termed as the Plenus Cold Event, has been recorded in many sites and sections in the northern hemisphere (Tethyan domain, Western Interior Seaway, proto-North Atlantic Ocean). But, its record and its impact on the biogeochemical cycles of carbon and nitrogen in the southern part of Central Atlantic Ocean has not been explored yet. Here, we present a detailed geochemical study of the Deep Sea Drilling Project site 367 (Cape Verde) based on a compilation of previous and new data of carbon and nitrogen isotope signals as well as trace element concentrations. The aim of this study is to better constrain the evolution of oxygenation in the water column and the associated changes in nitrogen cycle before and during the Oceanic Anoxic Event 2 in order to understand the paleoceanographic and environmental consequences of the Plenus Cold Event at one of the deepest site of the Central Atlantic Ocean. Our new dataset improves the resolution of the δ13C curve for this site, and we propose a new chemo-stratigraphic frame of the carbon excursion allowing for a better identification of the short-term negative carbon isotope excursion associated to the Plenus Cold Event. The detailed evolution of redox-sensitive proxies (Mo, U, V, Fe, Cu, Ni enrichments and Corg/Ptotal) and isotopic signals (δ13Corg and δ15Ntotal) evidence that this deep site was impacted by this cooling event. While anoxic conditions prevailed in bottom waters before and during the onset of the Oceanic Anoxic Event 2 characterized by euxinic NH4+-rich water column, this cooling event was accompanied by reoxygenation of the water column, which had affected the behavior of the redox-sensitive elements and caused changes in nitrogen biogeochemical cycling.

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Site 367: Cape Verde Basin

Cited by 7 publications

References 15 publications

Geochemical Evidence for Large‐Scale Drainage Reorganization in Northwest Africa During the Cretaceous

Geochemical Evidence for Large‐Scale Drainage Reorganization in Northwest Africa During the Cretaceous

Enhanced productivity led to increased organic carbon burial in the euxinic North Atlantic basin during the late Cenomanian oceanic anoxic event

The Plenus Cold Event Record in the Abyssal DSDP Site 367 (Cape Verde, Central Atlantic): Environmental Perturbations and Impacts on the Nitrogen Cycle

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